In a conventional delta-sigma modulator with a multi-bit quantizer, a multi-level digital-to-analog converter (DAC) is required to feedback an output signal of the delta-sigma modulator and to work with a loop filter and a quantizer to implement a close-loop system for noise-shaping function. However, a mismatch between the DAC cells contributes mismatch errors to worsen a signal-to-noise plus distortion ratio (SNDR) and Spurious free dynamic range (SFDR). A dynamic element matching (DEM) function is a well-known strategy to address the mismatch issue of the multi-level DAC, but the hardware complexity grows exponentially as a bit number of the DAC increases.